Electrical connection



July 22 1941. uso 2,250,156

ELECTRI CAL CONNECTIQN Filed June 2, 1939 INVENTOR y L. FERGUSON A TTORNEV Patented July 22, 1941 UNITED STATES PATENT OFFICE ELECTRICAL CONNECTION Lawrence Ferguson, New York, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application June 2, 1939, Serial No. 276,977

Claims.

This invention relates to a method of securing metal parts together and, more particularly, to the securing of such parts together when one at least of the parts is covered with insulating material.

The object of the invention is to obtain trical connection of two conducting elements, one at least of which is covered with insulating material without requiring stripping of the insulating material from the insulated element or elements prior to the making of the electrical connection.

The invention may be used in electrically connecting a terminal to an insulated conductor wire or may be used in electrically connecting a plurality of insulated conductor wires.

In the drawing, Fig. l is a view in perspective of an uninsulated element 01' conducting material suitably formed for connecting to an insulated conductor wire in accordance with the invention;

Fig. 1A is a view of a portion of Fig. 1 but modified to include a coating of relatively low melting metal on one of the surfaces;

Fig. 2 is a side elevational view of the part elecshown in either Figs. 1 or 1A associated with an insulated conductor wire and placed between spaced electrodes of an electrical welding device;

Fig. 3 shows the parts illustrated in Fig. 2 but in an advanced step relative to Fig. 2;

Fig. 4 shows two insulated conductors ready to be electrically connected in accordance with the invention and means for forming the electrical connection;

Fig. 5 shows the parts illustrated in Fig. 4 but in an advanced step relative to Fig. 4;

Fig. 6 is a view in" perspective of two insulated conductor wires placed between two relatively movable electrodes, the wires crossing each other and being encompassed by a metal ring and the parts arranged ready to form an electrical connection between the two conductor wires; and

Fig. 7 shows the parts illustratedin Fig. 6 in an advanced step in the iormation oi the connection.

In connecting an electrical terminal to an insulated conductor-wire, the common practice is to strip the insulating coating from a portion of the conductor wire before the electrical connection is made. In forming an electrical connection between two insulated conductor wires, the common practice is to strip the insulating coating from portions of the conductor wires before making the electrical connection.

My inventionprovides a method and means for electrically connecting the parts above mentioned without requiring stripping of the insulating material from the insulated parts prior it to the particular form shown and described,

it will be assumed that an electrical terminal is to be electrically connected to a conductor wire having an outer protective coating of insulating material, the insulating material being of such a nature that it can be melted or consumed under the action of heat applied through electrodes of an electrowelding machine and the terminal.

The terminal I, as shown in Fig. l, is a strip of metal bent into v-shape form and having a relatively long leg portion 2 and a shorter leg portion 3. The terminal I, as shown in Fig. 2, is placed between spaced and relatively movable electrodes 4 and 5 of an electrowelding machine. The electrodes 4 and 5 are the only parts shown of the welding machine since the showing oi other parts of the machine is not necessary to an 6 is held between theleg portions 2 and 3 ct the terminal and the bent portion 1 of the terminal passes partly around the conductor wire 6. The conductor wire 8 comprises an electrical conducting metal core 8 and a jacket 9 01' insulating material. It will be seen that when the terminal I is placed in the position shown in Fig. 2,,the terminal i forms an electrical conducting path irom the electrode 4 to the electrode 5, the path being by way of the bent portion I and being indicated by the dot and dash line shown in the figure. It is to be noted that, because or the current path provided by the bent portion 1 of the terminal, there will be no electrical are developed between the electrodes 4 and 5.

The electrodes 4 and 5 are relatively heavy and have a greater current-carrying capacity than the bent portion I or the terminal I. Due to this diilerence in current-carrying capacity of the parts and the passage of current through the parts, the temperature of the terminal i is considerably raised when the electrodes 4 and I are energized. The size and tom of the electrodes 4 and 5 and the current-carrying capacity of the welding machine employed and the currents applied will, of course, depend to some extent on the size of the terminal I and the kind of electrical connection it is desired to 101m between the terminal I and the conducting core l of the conductor wire 6 and also on the kind of material found in the jacket 8 of insulating material. The temperature ofthe leg portions 2 and 3 and'of the bent portion 1 of the terminal I at the points of engagement with the jacket O of insulating material, or at least one or these portions, must be raised to a suflicient extent to melt or consume the material of the insulating Jacket 8. The electrodes 4 and are relatively movable and are moved toward each other while the current is being applied. As the material of the jacket 9 is melted or consumed, the leg portions 2 and 3 of the terminal I are moved into engagement with the metal core 3 of the conductor 3 and to the position shown in Fig. 3. when the parts have reached this position, the leg portions 2 and 3 are in physical contact with the metal core 8 of the conductor 4 and, while there is still a current path through the bent portion I of the terminal, there is also a current path transversely through the metal core 3 01 the conductor wire 8, as indicated by the dot and dash lines in the figure. The terminal I, as shown in this figure, has been changed from its original V-shaped form to a U-shaped form and the bent portion I has been bent somewhat beyond the elastic limit of the terminal material so that it will remain in this form when released from the pressure of the electrodes 4 and I. In some cases only good electrical contact between the leg portions 2 and 3 of the terminal I and the metal core 8 of the conductor 6 will be required. If a morepositive and stronger connection is required, however, the terminal I may be readily electrowelded to the metal core 3 by simply applying surllcient current through the electrodes 4 and 3 and through the points of engagement of the leg portions 2 and 3 of. the terminal I and the metal core 3 to electrically weld the leg portions 2 and 3 to the core 8 of the conductor 6.

Insomecases allthatmayberequiredisto solder the terminal I to the metal core 3 01 the conductor wire 6. In this event, the terminal I is previously coated with relatively low melting point metal. As shown in Fig. 1A, a coating ID of relatively low melting point metal has been provided on the leg portions 2 and 3 of the terminal I and on the inner surface or the bent portion I. The terminal I coated with relatively low melting point metal Il may be placed between the electrodes 4 and 6 in the position shown in Fig. 2 and with the conductor wire 4 disposed in the V-shaped portion of the terminal. When the electrodes 4 and l are energized and moved toward each other, the temperature of the terminal I is raised to a suflicient extent to melt or consume the insulating Jacket 8 and bring the metal coating III to a molten condition. when contact is made between the leg portions 2 and 3 of the terminal and the metal core 3 of the conductor wire, the metal coating III will form a solder connection between the leg portions 2 and 3 oi! the terminal and the metal core 8 of the conductor wire 5.

To electrically connect two insulated conductors I employ the same principle as outlined above in connecting the terminal I to the in-l sulated conductor wire 8, to this extent, that I employ a member of conducting material to carry the electrical current from the electrode 4 to the electrode 5 while the connection is being made. The member of conducting material in this case, asshown in Figs. 4 and 5, is an incomplete ring II of conducting material. The ring II, however, may be completely closed. The ring II is placed about two parallelly an e condlwtol wires I2 and I3, each of which comprises a core I4 of metal and a jacket I5 of insulating material. The ring II is placed between the electrodes 4 and 5 of the electroweldlng machine. When the electrodes 4 and I are energized, the current will flow from one electrode to the other by way of the ring II. This will result in raising the temperature of the ring II. By the application of sufllcient current to the electrodes 4 and 5, the temperature of the ring II is raised to a suflicient extent to melt or consume the insulating material I5. As the insulating material I5 is melted or consumed, the electrodes 4 and 5 are moved to the position shown in Fig. 5. In this figure the ring II has been somewhat flattened and brought into physical contact with the metal cores I4 01 the two conductor wires. The ring II thus forms an electrical connection between the metal cores I4 oi the conductor wires. If the electrowelding oi the ring II to the cores I4 is required, this can be accomplished by the application of suilicient current by way oi the electrodes 4 and I and the ring II and by suitably pressing the ring II against'the cores I4. A solder connection may be formed between the cores I4 and the ring I I by previously coating the ring II with solder and maintaining the ring II at a required temperature to melt the solder while the ring II is being pressed into engagement with the cores I4 01 the conductor wires.

The same principle is also followed where it is desired to form an electrical connection between two insulated conductor wires crossing each other at an angle. To form such a connection as shown in Figs. 6 and 7, the insulated conductor wires I6 and I1, each oi which comprises-a core II o! conducting material and a sleeve I! of insulating material, are placed one above the other at the required angle. An incomplete or complete ring 23 of metal and o! a diameter sumcient to encompass the two wires is disposed around the wires at the point of crossing. The ring 23 is placed between the spaced electrodes 4 and 5 oi the welding machine so that it forms an electrical connection between the electrodes 4 and I. when a suitable current is applied through the electrodes 4 and 5, the ring III is heated to a suilicient extent to melt or consume the insulating sleeves I3 01 the conductor wires I6 and H at the point of crossing of the conductor wires. As the insulating material on the conductor wires is melted or consumed, the electrodes 4 and i are moved toward each other to the position shown in Fig. 'I so that the cores II of the conductor wires are brought into physical contact with each other and with the ring 20 and so that the cores I3 and the ring- 20 are deformed to a suiilcient extent to retain the wires in this position. By properly regulating the current applied through the electrodes 4 and 5 and by way of the ring 23 to the cores II of the conductor wires, the wires may be welded together at their point of crossing and the ring 20 may be welded to the conductor wires at this point.

In making connections between metal parts as above described, the size and tom of the metal part used in carrying the current irom one electrode o! the welding machine to the other and around the desired points 01 connection while the connection is being made and the amount of current and the duration of its application will depend somewhat on the type of connection required, the character of the insulating material to be melted or consumed, and the material of which the metal part and parts to be connected are made. I have foundthat by the method and arrangement described a terminal oi brass composition may be connected to a copper conductor wire having a coating of insulating enamel, rubber, cotton, or silk without previously stripping the coating of insulating material from the copper conductor wire. I have also found by actual experiment that, by using my invention, an electrical connection may be formed between two copper wires coated with a double serving of insulating thread and lacquered without previously stripping the insulating material from the copper wires.

I have, for instance, formed an electrical connection between two No. 22 gauge enameled wires covered with two servings of cotton and lacquered with cellulose acetate in the manner described. In making'this connection, the insulated wires were enclosed in a nickel band bent from a strip of such material approximately .025 inch thick and .110 inch wide. About twenty pounds pressure was applied to the electrode to squeeze the parts together as the insulation was bumed away. The welding current was allowed to flow for one-half second. suflicient heat was generated in this time to bring the nickel band to a temperature of approximately 1200 C. This resulted in burning away the insulation at the points of contact and the formation of an electrical weld between the metal parts. After the welds were made, attempts were made to break the welds, but the welds were found to be stronger than the wires. I have found, by microscopic examination, that these joints are actually welded and, by electrical tests, that the electrical contact is permanent. Nickel was chosen for the material of the band because of its ability to withstand a comparatively high temperature without melting or breaking apart under the pressure applied. Other reasons for the choice of nickel were the ease and speed with which it wets and alloys with copper, its comparatively high electrical resistance enabling smaller welding currents to be used and its freedom from tarnish films which might interfere with the flow of current and welding action.

Although I have mentioned nickel as being a suitable material for use in the band, it is obvious that various other materials may be used for the same purpose without departing from the spirit of the invention, the scope of which is indicated in the following claims.

What is claimed is:

1. A method of forming an electrical connection between metal parts, one at least of which is covered with insulating material, comprising placing said parts between a pair of spaced and relatively movable electrodes of an electrical current-carrying machine and so that said insulating material on one of said parts is in contact with another of said parts, providing in one of said parts a metal electrical current-carrying path from one of said electrodes to the other and in by-pass of the point of contact of said parts, applying suilicient current through said electrodes and said current-carrying path to raise the temperature of one of said parts to a suincient extent to remove said insulating material from the point of contact of said parts and moving said electrodes toward each other as the insulating material is removed and until said parts are electrically connected.

2. A method of forming an electrical connection between two conductor wires, individually covered with insulating material, comprising placing said conductor wires between spaced and relatively movable electrodes of an electrical current-carrying machine, placing a band of metal around said conductor wires and between the insulating covering of said wires and said electrodes, moving said electrodes to press said band toward the conducting elements of said wires, applying sumcient current through said electrodes and by way of said band to raise the temperature of said band to a sufiicient extent to melt said insulating material, pressing said band into engagement with the conducting elements of said wires while said insulating material is being melted and applying sufilcient electrical current through said band and said wires to electrically join said band to the conducting elements in said wires.

3. A method of forming an electrical connection between conductor wires crossing at an angle and individually covered with insulating material, comprising placing a metal band around said wires at the point of crossing and placing said wires and said band between and so that said metal band is in contact with spaced and relatively movable electrodes of an electrical current-carrying machine, applying suflicient current through said electrodes and by way of said band to raise the temperature of said band to a sumcient extent to consume the insulating cov-.

erings of said wires and moving said electrodes toward each other while said insulating coverings are being consumed and until the conducting elements of said wires and said band are electrically connected at the point of crossing of said wires.

ficient to remove the insulation from at least a portion of said insulated element end applying sufflcient pressure to said elements to bring them into electrical contact with each other.

5. A method of connecting an electrical terminal to a conductor wire covered with insulating material, comprising forming said terminal to at least partially encompass the insulating material on said wire, placing said wire within said terminal so that the insulating material on said wire is engaged on two sides by said terminal, placing said terminal in electrical engagement with oppositely disposed spaced electrodes of an electrical welding apparatus, electrically energizing said electrodes to pass a heating current through said terminal suflicient to remove the insulating material from said wire at the points of engagement with said terminal and relatively moving said electrodes to press said terminal into ensasement with said conductor wire and electrically connect said terminal to said conductor.

LAWRENCE FERGUSON. 

